Fluid pressure servomotor



Dec. 14, 1948. R. M. NARDONE FLUID PRESSURE SERVOMOTOR Original Filed 001:. 22, 1940 2 Sheets-Sheet l INVENTOR. Romeo M. Nat/done AT RNEY.

Dec. 14, 1948. R. M. NARDONE mm) PRESSURE sEavon lo'roR Original Filed Oct. 22. 1940 I 2 Sheets-Sheet 2 e MM d Q. 2 j w mm w PM 7/ w mm Y O a a w m of a part line 2-:2 .ofFig. 1;

Patented Dec. 14, 1948 Romeo'M. Nardone, Teaneck,

Bendix Aviation Corporation,

N. "J., assignor "to Teterboro, N11,

1 acorporationof Delaware Originalapplication October 22, .1940, .Serial No. 362,271. -DiVided and this application August .10, .19.43,'Serial-N.o. 498,123

2 Claims.

. ."Thisinvention"relates to fluid pressure 'systems, and particularly to the structure and .operation of a servo-element forming part-'of-a fluid pressure system, and operable :in response to .fiuid, pressure or parts toijbe actuated.

An object of the invention is to provide a servo-motor with a valve of the plunger type,

.shiftable in either direction along the line of its longitudinal axis,.and cooperatingwith a second ..valve element rotatableabout said longitudinal axis, wherebylongitudinalishifting,of .the plunger isfacilitated; the constant rotationof the cooperating valve element being effective to offset any slight deviation from true alignment, or any veccentricityof bearings or other parts, which imisalignment or eccentricity would otherwise cause binding or jerky operation.

Anotheriobject is to .proVide a. novel follow-up mechanism, involving a third valve element .co-

operating with the other two in such manner as to produceautomatic cessation of "fluid flow to and from the servo-motor, at the instant when theupart .to be .moved has reached the intended setting.

Other objects and "features of the invention will become apparent from inspection of .the

following specification when read with reference to the accompanying drawings wherein are illustrated the preferred embodiments of the invent'ion. 'It'fis to .be understood, however, that the drawings are for the purpose of illustration only,

andare not designed as a definition. of the limits ,of-the invention, reference being had to the appended claims for-this purpose.

film the drawings:

' Fig. '1 is a longitudinal sectional view of a devicelem'bodying certain features of the invention; 'Fig. .2 is a transverse sectional view along the 11mg; .3 is a'longitudinal sectional .view of .a device embodying all.'features of theinvention; and

Eig...4 "is.a transverse sectional .yiew .of that .po1:tion..of the device .ofiEig. .3 which is not iully Tillustrattedin .said' :Fig. .3. 1

Theinventionis shown as embodied in 1a sectional casting whoselower section .5, constituting .anoil reservoir includes the lower part .of alledge .34 adapted to receive the flange 35 of an endplate 33 cooperating with .the upper section .31 'of the unit to form a housing .for 'a gear '4 which constitutes part of the driving connections be- "tween driving shaft 38, pinion 39, and pump rotor 2, the latter being mounted on the gear "driven shaft 9 and rotatable therewith 'by-"vir'tue to control the degree ofmovement Ill plunger valve'l ll 'feren'tial and radial ports sleeve -4! constitutes the port/'8.

--which passes v alve right of piston I5,

left as the -oil on the left thereof returns'to the "reservoir by way of passages 56, H,

as far as 'radial port"3 l. 'Which passes plun'ger exposed-to the=space 35, and the oil :flow is the reverse of that firstindicated.

shiftable spring of the "'pin connection 3. Extended :endzzlll .of shaft Q is bored to form a chamber in. which reciprocates and therebycontrols flow :of oil,or other fluid, through the circum- .8, II and 12in the end 41 of the rotating shaft 9. This second valve element above referred to as cooperating with plunger valve to to govern the operation of the servoelement "-1 5. As shown, servo-element I5 is in the form of a piston reciprocable in a cylinder 43 mountedin a pocket 44 of the housing, and servsleeve-like ing to actuate a work performing shaft 20 by "reason of 'the intervening connecting rod 18 and crank-arm IS.

The pump .2 may be of the Gerotor type having inner and outer rotors with inter-meshing teeth 21, 22 '(Fig. 2) as more fullydisclosedinthe Hill patents, such as Patent No. 15682564.

The pump iz draws oil from reservoir 5 through "a-str-ainer 6 and inlet passage 23, and delivers it under pressure to outlet passage 1 and valve With the plunger-valve It] in the central (neutral) positiornports H and !:2 of the sleeve valveare covered, hence the onl escape path f'or the' pumped oil is by way of transverse passage 5D to valve 51 (Fig. 2) which-when the "pressure becomes su'fficiently high-is pushed off its seat bythe pressure acting thereupon, overcoming the opposition of spring 52. The oil 5| returns to the'reservoir 5 byway of return duct 53.

"When plunger valve 10 moves to the right, oil flows from port Bthrough ports 12 and M to the moving the said piston to the ll, 3| and 32. the passage 11 extending centrally of the valve, to a Space 36 "communicating with the reservoir 5. When 'valve =10 moves to the left, the port 12 is lt' will' bernoted that the crank-arm housing "42 =cooperates with cylinder '43 to form the com- "pletefluid chamber on theri'ght of piston f5; the "only means "of egress I therefrom The housing .42'is fluid-tight at all points, including the' spaoe around shaft Zll being by port I' l.

(See Fig.4.) Plunger!!! is balanced and retained in its -neutral position'by opposmg springs 22 and 13 which may be adjusted,=as by a screw 24 and a thumb nut 25. "The screw 24 operates upona abutment in the "form of-a iflanged -plug 2 9 which is -'-telescopically received within the outer extension 30 of the valve member l0. Movement of the screw therefore varies the deflection of spring l3 and hence eflects a balancing of the valve member ID, in conjunction with pre-set spring 22. The latter spring abuts the stationary support 40 at one end, while its opposite end abuts flange MA of valve extension 30. Thus it opposes, and is balanced by, spring l3.

The central portion of the plunger I is flattened for the attachment of arm 26 which is in turn secured to rock shaft 21. To this rock shaft is connected a control member on link 28 movable by hand or by any part movable to control the shifting of the valve member l0, and thereby control the action of the servo-motor I5. By this means the movement of the shaft 20 may be controlled from a remote point.

It will be seen that pump 2 serves a twofold purpose. First, it is the source of fluid pressure for operation of the servo-piston I and secondly, its action in constantly rotating the outer portion ll of the valve is such as to facilitate reciprocation of the inner portion ID of said valve; the constant rotation of the outer part 4| being effective to offset any slight deviation from true alignment, or any eccentricity of bearings on other parts, any of which irregularities would otherwise interfere with smooth and facile operation of the reciprocable inner portion of the valve.

Another feature, which is not illustrated in Figs. 1 and 2, but as shown in Figs. 3 and 4 in the manner in which it may be most readily applied to the above described mechanism of Figs. 1 and 2, is the follow-up mechanism by which the valve is automatically restored to the neutral or cut-off position, as soon as the operated shaft 20 reaches the position corresponding to the degree of movement of the actuating part 28. As shown in Figs. 3 and 4 this f01loW-up mechanism is operatively connected with the operated shaft 20, the connection being preferably at the end of said shaft which is remote from the hous ing 42 in which said shaft 20 is adapted to oscillate in response to the movements of the actuating piston I5; the movement of the shaft 20 being facilitated by the provision of friction reclucing bearings 60 and GI, and the escape of fluid from the housing 42 being guarded against by the provision of the sealing means 62 which is interposed between the bearings 66 and 6!.

' The operative connection between shaft 28 and theffolloW-up mechanism preferably takes the form of a pinion 64 secured to the lever 63 by suitable means 65 and having a sufficient number of teeth to remain at all times in meshing relation to a correspondingly toothed sector 66 whose apertured upper end receives rock shaft 61 to which it imparts movement, the said rock shaft having its bearings in a transversely extending bore in the upper portion 68 of the housing 42 and prortruding therefrom to receive the apertured circular end of a toothed sector 69 which meshes with a rocking element 'H which, as shown, is integral with a long tubular valve element I2 having ports BI, 82 and 83 whose spacing corresponds to the spacing of the ports 8, II and I2 of the associated valve structure shown in Figs. 1 and 2 and reproduced in Fig. 3. Throughout the range of movement of the parts, these ports 8!, 82 and 83 remain in registry with the ports 8, H and I2, respectively, of the valve element 4!, but when slidable valve element in is in the neutral or cut-off position, the port 8-8! is 4 cut off from both the port ll82 and the port l2-83 by the blocking action of lands 84 and 35 as they cover ports 82 and 83, respectively; therefore no flow of fluid to either side of the piston Hi can occur in such neutral position of the shiftable element Ill.

The mechanism for shifting the element I0 is substantially the same as heretofore described and illustrated in Fig. 1, except that the means for translating the shifting of arm 28 into a corresponding shifting of the slidable valve element l 0 takes the form of a pinion l6 and corresponding aligned teeth I? out along the surface of a portion of the shiftable valve element l0 adjacent the longitudinally extending slot 73 out in the surface of the follow-up element 12, wherefore movement of the said element 12 between its limits of travel is possible without interference with the actuating pinion 16 which causes a shifting of the valve element I0 in response to a rocking of the actuating shaft 14 corresponding to the actuating shaft 21 of Fig. 1. To facilitate illustration of this feature of the invention, the pinion l6 and the rack H are shown in Fig. 3 as being shifted ninety degrees from their actual locations, but it is to be understood that pinion i6 is integrated with shaft 14 and turns with said shaft about a common axis. Shaft 14 is journaled in a bearing 18 secured to the frame or housing and is movable through any desired portion of its arc of movement under the control of the actuating member 28. The follow-up element 1 l--'l2 is held against rotation, as is also the shiftable valve element 10, by the restraining pin 89 which is mounted. in the extending bearing portion 85 of an end-plate 8'! which registers with a boss on the housing, the said pin 89 being adapted to extend into slots 90 and Si formed in the elements 12 and I0, respectively, and thus preventing rotation of either element while permitting longitudinal movements thereof in response to rotation of the toothed driving ele ments 69 and 15, respectively. With this construction it will be apparent that movement of operating shaft 14 through any desired angle, say ten degrees, produces a corresponding rectilinear movement of the valve element In within the valve element 12 and the rotating valve element 4! of Figs. 1 and 3. If this movement is such as to produce clockwise rotation of the pinion 76 as viewed in Fig. 3, the resulting leftward shifting of element II] will withdraw lands 84 and 85 from covering relation to ports 82 and 83, and will serve to establish communication between the supply port 8 and the ports I l and 82 leading to the left-hand side of the piston [5. The result will be a corresponding rotation of the shaft 20 and the lever 63 operatively connected thereto to a corresponding arc of say ten degrees. There will simultaneously occur a rocking of the shaft 67 through a similar arc, and a resulting shift of the follow-up valve element 12, to carry ports 82 and 83 toward the new position of lands 84 and 85, respectively. When such follow-up is completed, communication between the port 8, on the one hand, and the port ll82 on the other, will again be cut off, as will also communication between port I2-83, on the one hand, and annular outlet 32 on the other. When this occurs, and it will occur simultaneously with the arrival of the operated lever 63 at a position corresponding to the amount of shifting of the operating member 28, all flow of fluid to and from the chambers of piston IE will cease, and resulting equilibrium will prevent further movement of 5 the piston [5. Thus the desired setting of the operated member 63 is brought about in response to the initial operation of the actuating member 28 and without any further manual supervision or intervention.

It will be obvious from the foregoing that the member 63 to be operated may be shifted in the opposite direction in response to an opposite shifting of the actuated member 28, as the valve mechanism will on such occasions operate first to establish communication between the supply passage 88|, on the one hand, and the passage M on the other, while connecting the passage 16 with the reservoir 5 by way of the longitudinally extending passage ll, port 3 I, and annular outlet 32; and as the actuated member 63 moves to- Ward the desired setting, the follow-up valve 12 will move toward the cut-off position to terminate the flow from the supply passage 8 at the moment of completion of the shift of the operated member 63.

This application is a division of my previous application No. 362,271, filed October 22, 1940, now abandoned.

What is claimed is:

1. The combination, with a servo-motor, of valve mechanism for controlling fluid flow therein, said mechanism including a pair of relatively movable nested valve elements, the inner of which elements is reciprocable and the outer of which elements is rotatable and provided with a plurality of ports communicable with each other in a predetermined paired relation, means carried by said inner element for establishing said paired relation, said inner element having an outward extension, resilient means mounted on said extension, for yieldably holding the inner element in a position with respect to said ports, to render said first-mentioned means ineffective, means for adjusting said resilient means to insure holding said inner element in said position, and means for shifting said inner element in either direction from said position to render said first-mentioned means eiiective.

2. The combination, with a servo-motor, of valve mechanism for controlling fluid flow therein, said mechanism including a pair of relatively movable nested valve elements, the inner of which elements is reciprocable and the outer of which elements is rotatable and provided with a plurality of ports communicable with each other in a predetermined paired relation, means carried by said inner element for establishing said paired relation, said inner element having an outward extension, resilient means mounted on said extension, including cooperating oppositely acting springs for yieldably holding the inner element in a position with respect to said ports, to render said first-mentioned means ineffective, means for adjusting one of said springs to insure holding said inner element in said position, and means for shifting said inner element in either direction from said position to render said first-mentioned means efiective.

ROMEO M. NARDONE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 533,143 Schmaltz Jan. 29, 1895 1,600,542 Gagg Sept. 21, 1926 1,972,852 Albright Sept. 11, 1934 2,047,922 Seligmann July 14, 1936 2,117,891 Kalin May 17, 1938 2,139,878 Carlson Dec. 13, 1938 2,204,640 Woodward June 18, 1940 2,223,136 Tweddell Nov. 26, 1940 2,258,094 Keller Oct. 7, 1941 2,270,059 Kahr Jan. 13, 1942 

